The present invention relates to a liquid crystal display device. A liquid crystal display panel employed in the liquid crystal display device comprises a pair of opposed substrates sealed along their peripheries to form an envelope for a layer of liquid crystal material and a plurality of electrodes for defining pixels on an inner surface of at least one of said pair of opposed substrates. Each pixel has a function of controlling the amount of light passing therethrough.
In general, the liquid crystal display devices are known which comprise a liquid crystal display panel using a pair of transparent substrates and a backlight disposed behind the liquid crystal display panel such that images are produced by controlling the amount of light passing through the liquid crystal display panel from the backlight.
The backlight is housed in a frame made of resin (hereinafter referred to as a lower case). The liquid crystal display panel is placed on the lower case so that the liquid crystal display panel is illuminated by the backlight.
The lower case serves mainly to house the backlight, supports the liquid crystal display panel and serves as a mask for projecting light from the backlight onto an area for displaying images of the liquid crystal display panel (hereinafter referred to as a display area).
Such a technique is disclosed in U.S. Pat. No. 5,432,626 (Application No. 29,622) issued on Jul. 11, 1995, for example, which employs a case for housing a backlight and an intermediate frame interposed between the case and a liquid crystal display panel.
But with a tendency toward large-sized display area, there arises a problem with the prior art liquid crystal display device that the mechanical strength of the lower case needs to be increased for housing a large-sized backlight and consequently the thickness of the lower case is required to be increased. This increases the width of the non-useful display area at the borders of the liquid crystal display panel (hereinafter referred to as a border area).
As explained above, the lower case supports the liquid crystal display panel and serves as a mask for projecting light from the backlight onto a display area of the liquid crystal display panel. With this structure, there is a possibility that shading occurs at the peripheries of the display area of the liquid crystal display panel viewed from the observer side.
Since the thickness of portions of the lower case serving as a mask is relatively greater, the portions block the light from the backlight and cause the shading at the peripheries at the display area of the liquid crystal display panel viewed from the observer side.
It is an object of the present invention to solve the above problem with the prior art and to provide a liquid crystal display device capable of securing a sufficient mechanical strength of the lower case without increasing the border area of the large-sized liquid crystal display panel.
It is another object of the present invention to provide a liquid crystal display device free from occurrence of the shading at the peripheries of the display area of the liquid crystal display panel viewed from the observer side.
The above-mentioned objects and novel features of the present invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings.
For achieving the aforesaid object, a liquid crystal display device according to an embodiment of the present invention comprises: a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of upper and lower substrates, an illuminating light source disposed behind the liquid crystal display panel, an upper case made of metal having a sidewall bent back from a periphery of a front portion thereof and a window approximately corresponding to a display area of the liquid crystal display panel, a lower case made of resin for housing the illuminating light source in a recess thereof, and an inner frame made of metal having an opening for allowing light from the illuminating light source to be directed toward the liquid crystal display panel and interposed between the liquid crystal display panel and the lower case, the upper case and the lower case being clamped together after stacking the liquid crystal display panel, the inner frame and the illuminating light source in the order named between said upper case and said lower case.
For achieving the aforesaid object, a liquid crystal display device according to another embodiment of the present invention comprises: a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of upper and lower substrates, an illuminating light source disposed behind the liquid crystal display panel, an upper case made of metal having a sidewall bent back from a periphery of a front portion thereof and a window approximately corresponding to a display area of the liquid crystal display panel, a lower case made of resin for housing the illuminating light source in a recess thereof, an inner frame made of metal having an opening for allowing light from the illuminating light source to be directed toward the liquid crystal display panel and interposed between the liquid crystal display panel and the lower case, and a transparent plate fitted within the opening in the inner frame, the upper case and the lower case being clamped together after stacking the liquid crystal display panel, the inner frame and the illuminating light source in the order named between the upper case and the lower case.
The construction of the present invention enables the metal inner frame to reinforce the lower case and consequently eliminates the need for increasing the thickness of the lower case, namely avoids the increase in the so-called border area of the liquid crystal display panel.
Employment of metal for the inner frame makes the thickness of the inner frame thin. In directing light from the backlight by the inner frame only onto the display area of the liquid crystal display panel, it is possible to prevent occurrence of the shading at the peripheries of the display area of the liquid crystal display panel when it is viewed from the observer""s side by accurately positioning the edge of the opening of the inner frame.